Conventionally, as described in Patent Literature 1, a magnet molding method A is known, in which a plurality of magnet insertion holes are provided for a laminated core body of a laminated rotor core, and a magnet piece is inserted and fixed in each of the magnet insertion holes. In this method, as shown in FIG. 8, magnet pieces 72 are inserted in a plurality of magnet insertion holes 71 provided in a radially-outward region of a laminated rotor core 70. After the laminated rotor core 70 is heated to a certain temperature, a molding resin 75 is injected from an upper die 73 (or a lower die 74) into the magnet insertion holes 71. By curing the molding resin 75, the magnet pieces 72 are fixed to a laminated core body 76. A reference numeral 77 denotes a carrier fixture, a reference numeral 78 denotes an upper fixing plate, a reference numeral 79 denotes a lower fixing plate, a reference numeral 80 denotes a guide post, and a reference numeral 81 denotes a plunger.
However, in the method described in Patent Literature 1, the molding resin 75 remains on a resin passage portion of a surface of the laminated rotor core and a gate portion which connects to the magnet insertion hole 71. Therefore, after the molding resin is filled, a process to remove the resin remained on the surface is needed. Thus, Patent Literature 2 discloses a magnet molding method B wherein a dummy plate is used.
In the magnet molding method B, as shown in FIG. 9, a dummy plate 82 is disposed on a top surface of a laminated core body 76. The molding resin 75 is injected through a gate 83, a resin injection hole, provided on the dummy plate 82. Thus, the injected molding resin 75 adheres to and remains on a surface of the dummy plate 82, not on the top surface of the laminated core body 76. Therefore, by removing the dummy plate 82 from the laminated core body 76, the residual molding resin is also removed at the same time. A reference numeral 84 denotes a resin passage provided in the upper die 73.